Isolation and Expression of a Full Length cDNA Clone Encoding for the Low Molecular Weight Salivary Mucin Protein Backbone Human Sumandibular-sublingual (HSMSL) saliva contains a low molecular weight mucin(MG2), that appears to be structurally and functionally distinct from a high molecular weight mucin(MG1), also found in HSMSL saliva. MG2 has molecular weight ~ 120 kda; 70% of which is composed of oligosaccharide chains that are 2-8 residues in length. MG2 appears to function in both the lubrication of host oral tissues and bacterial clearance. Molecular biology studies in our lab have yielded significant data concerning the nature of the MG2 protein with regards to size, the DNA sequence encoding the complete peptide backbone, and tissue specific expression of MG2 mRNA. We have isolated a full-length cDNA clone encoding for the MG2 peptide backbone by screening a ~gt11 human submandibular gland cDNA library with rabbit polyclonal antisera to deglycosylated MG2. Proposed studies utilizing this clone include the production of recombinant MG2 molecules in expression systems that should produce recombinant that are distinct with regards to glycosylation. Expression of MG2 in E.coli and baculovirus expression systems should result in MG2 apomucin and aberrantly glycosylated MG2 glycoprotein, respectively. These MG2 recombinant molecules will be compared to native MG2 in bacterial binding assays and lubrication studies. The interpretation of the results will two- fold: a) we will be able to determine whether these systems are capable of producing functional mucin molecules and b) we will be able to determine the role of oligosaccharide side chains in mucin functions. This data can be employed in the engineering of an artificial of an artificial saliva for treatment of xerostomic patients. Key Words: Human, Saliva, Mucin